Pictorial representation reproducing head



Feb. 10, 1953 N. R. GUNDERSON Filed Oct. 9, 1946 PICTORIAL. REPRESENTATION REPRODUCING HEAD 7 Sheets-Sheet 1 lll JNVENTOR,

Feb. 10, 1953 N. R. GUNDERSON 2,628,150

PICTORIAL REPRESENTATION REPRODUCING HEAD Filed Oct. 9, 1946 '7 Sheets-Sheet 2 0 so I l as a/ 1 5 3 NbR/wv Egan/950m mmvron 1953 N. R. GUNDERSON 2,628,150

PICTORIAL REPRESENTATION REPRODUCING HEAD Filed Oct, 9, 1946 7 Sheets-Sheet 5 E ELIIIHINIEIMHII: --!l! a, iifu'nflIlMm Y 90 a9 AbRmA/R GUNDERSON,

IN V EN TOR.

A TTORNEY.

Feb. 10, 1953 N. R GUNDERSON 2,623,150

PICTORIAL REPRESENTATION REPRODUCING HEAD Filed Oct. 9, 1946 7 Sheets-Sheet 4 NORMAN R. GUNDERSo/V,

IN VEN TOR.

BY d? A T TORNE Y.

Feb. 10, 1953 N. R. GUNDERSON PICTORIAL REPRESENTATION REPRODUCING HEAD N, 5 w m mm h D E s w w w R m y a N 7 m W Filed Oct. 9, 1946 A T' TORNE Y.

Feb. 10, 1953 N. R. GUNDERSON 2,628,150

PICTORIAL REPRESENTATION REPRODUCING HEAD Filed Oct. 9, 1946 7 Sheets-Sheet 6 Noam/v R GUNDERLSO/V uvmvroze.

m T TOE'NE K,

Feb. 10, 1953 N. R. GUNDERSON PICTORIAL REPRESENTATION REPRODUCING HEAD 7 Sheets-Sheet 7 Filed 001:. 9, 1946 NORM/V A. GUNDERSO/V,

JNVENTOR.

ATTORNEY Patented Feb. 10, 1953 PICTORIAL REPRESENTATION REPRODUCING HEAD Norman R. Sanderson, Pasadena, Calif. Application Gctoher 9, 1948, Serial No. 702,174

11 Claims.

This invention relates generally to reproducing heads adapted for use in making colored pictorial representations, facsimiles, or reproductions of colored subjects. More specifically, it relates to reproducing heads adapted to mix various colored inks and a black ink in accordance with electric signals corresponding to the various colored inks and the black ink, and to apply said mixed atomized inks upon succeeding small, elemental areas or points of a suitable medium, such as paper or the like (which maybe mounted upon a suitably driven rotatable and axially movable drum) so that a reproduction in substantially natural eclors (or desired colors) is obtained.

This application is a continuation-in-pait of my parent application, Serial No. 426,220. filed January 9, 1942, now Patent 2,413,786, issued January 2, 1947, and the reproducing heads described, iliustrated and claimed herein are adapted for use in the system disclosed in said parent application, or in the systems disclosed in my copending application, Serial .No. 702,173, filed October 9, 1946, now Patent No. 2,560,567, dated July 1'7, 1951, or in many other color reproduction systems, as will be apparent to those skilled in the art.

Prior art reproducing heads have numerous disadvantages. For example, most prior art reproducing heads have very slow response. In other words, the flow of the various inks lags, to a considerable extent, behind the corresponding electric signal, and if :the electric signal is changing rapidly, the flow of the corresponding ink cannot follow the electric signal, and distortion results. Also, most prior art reproducing heads do not properly mix and atomize the inks whereas the reproducing heads of my invention have exceedingly fast accurate response with distortion minimized.

Generally speaking, my invention comprises: an air conduit provided with means for supplying air under pressureto said conduit; at least one nozzle provided with a fixed opening directed into the air stream from said air conduit; an ink conduit for supplying the nozzle with ink; and means for causing ink flow to the nozzle. The term, ink, as used herein-includes any fluid solution dispersion or suspension adapted for use in the system.

In the preferred embodiments of my invention I have employed three colored ink nozzles and a clack ink nozzle; however, any desired number might be used.

In the first embodiment of my invention the above referred to fin-sans for causing ink flow 2 comprises, a piston reciprocable in a cyl nder in response to interacting magnetic fields, one of which is controlled by the electric signal correspending to that ink.

In the second embodiment of my invention, the above referred .to means for causing ink now comprises means for generating and modulating a high frequency oscillatory electric current in accordance with an electric signal corresponding to that colored ink, and applying said modulated high frequency current to the ink for heating and expanding same.

With the above points in mind:

It is an object or" this invention to provide an improved reproducing head having an exceed ingly fast response and a minimum (ilStGltion.

t is a further object of this invention to provide an improved reproducing head having an exceedingly fast response and a minimum of div tortion wherein the flow of ink is caused by electromagnetically actuated reciprocatingmeans.

It is a further object of this invention to provide an improved reproducing head having an exceedingly fast response and a minimum of dis tortion wherein the flow of ink is caused by electrically controlled heating and expansion of the ink. V v

Other and allied objects will become apparent to those skilled in the art after a careful examination and perusal of the illustrations, specifi cations and claims appended hereto.

For purposes of illustration reference had to the following drawings, of which:

Fig. l is a diagrammatic drawing of a reproducing head cooperating with a driven rotatable and axially movable drum upon which is mounted the medium upon which the reproduction is to he formed.

Fig. 2 is a side elevation, partly broken away, of one form of reproducing head.

Fig. 3 is a plan view of the reproducing head.

Fig. 4 is a bottom view of the reproducing head.

Fig. 5 is a section taken along the plane V-V of Fig. 2.

Fig. 6 is an enlarged View through a portion of the reproducing head.

Fig. 7 is a vertical section taken along the plane VIIVII of Fig. 6.

Fig. .8 is an isometric perspective of the reproducing head with a portion thereof cut out.

Fig. 9 is another isometric view of the reproducing head with portions cut out along vertical and horizontal planes.

Fig. 9a is a perspective, diagrammatic reprewill sentation of the conduits associated with a single nozzle of the reproducing head.

Fig. 10 is a perspective view of the lower portion of the reproducing head with a section cut away.

Fig. 11 is a side elevation of one of the moving coils used in the first form of my reproducing head.

Fig. 11a is an enlarged transverse section of the coil taken on line mat-Km of Fig. 11.

Fig. 12 is a plan view of a modified arrangement of nozzles for use in the reproducing head.

Fig. 13 is a vertical section of Fig. 12 taken along the plane XIII-XIII.

Fig. 14 is a top plan view of a second embodiment of the reproducing head of my invention, with the top plate and nozzles removed.

Fig. 15 is a vertical section of the second embodiment of the reproducing head of my invention.

Fig. 16 is a diagrammatic block electrical drawing, illustrative of one way the second form of reproducing head may be controlled.

Fig. 17 is a wiring diagram schematically illustrating one form of modulator for use with the second form of reproducing'head of my invention.

More specifically, the reproducing head generally indicated at 32 in Fig. 1 consists of a suitably driven rotatable and axially movable drum adapted to mount a suitable medium such as paper or the like and which need not be described in detail. By referring to Figs. 1-13, one form of reproducing head is there shown. As

there shown, "the body of the reproducing de- :1"

work 84. Extending vertically through the center of the armature 82 is a hollow rotatable drive shaft 85 provided with a mitre gear 86 at its lower end. This shaft is periodically partially rotated, the partial rotation of this shaft being in timed relation to the rotation of the reproducing drum. I

The mitre gear 86 is shown in engagement with another mitre gear 81 carried by intermittently driven shaft 88 suitably journaled in brackets, the shaft 88 also carrying a stop arm w 89 adapted to mov against stop pins 90 and SI, as best shown in Fig. 5. The reversible motor 92 drives a gear 93 at suitably timed intervals, the gear 93 being fiexibly coupled to themotor 92 and in engagement with a gear 94 which is journaled on shaft 88 and is provided with a pin 94' capable of striking the arm 89 to rapidly move it from the position indicated in full lines in Fig. 5 to that shown in dotted lines and vice versa, in timed relation to the reproducing drum. The motor 92 may be interlocked or controlled by the motor drive to the reproducing drum.

As shown in Figs. 6 to 13 inclusive, the armature 82 is provided with an upward extension or head which may be made of a lower block I00 and an upper block IDI suitably attached thereto, the blocks being preferably of non-magnetic material. Extending through these blocks centrally through the center of the intermittently rotated shaft s5 is an aircoiiduit lilt 'connected to a source of air at a sufilciently high pressure to atomize ink supplied to such air stream through a plurality of nozzles H35, H36, I0! and 108 carried by the upper block ml. The tips of these nozzles are provided with minute perforations or openings (on the order of 0.004 of an inch). The ends of these nozzles are preferably placed in alignment with the inner surfaces ofthe air conduit I03 so as to assure substantially complete removal of all ink ejected by the nozzles without creating undesirable suction effect on the ink within the nozzles. Although the nozzles shown in Figs. 6 and 7 are pointed transversely to the air stream, other arrangements may be used, such as for example, that shown in Figs. 12 and 13 wherein the nozzles are upwardly extended into the air stream emitted I by conduit 33.

In the drawings a reproducing head having four nozzles is shown, three of these nozzles being adapted to supply colored inks, the fourth nozzle being associated with a source of black ink. In accordance with the present invention, the rate of feed of the inks through the nozzles is controlled in accordance with the variations in the electrical input signals to the reproducing head. By varying the pressure on bodies of ink to which the nozzles are connected, the nozzle 05, for example, may be in communication with a conduit H39 leading to an enlarged chamber lit, the open side of such chamber being closed by a movable piston Ill carried by a movable coil H2. The coil itself is positioned within the magnetic field between the armature 82 and the magnetic frame 8i. Each of these moving coils such as H2, is made so as to slidably fit within the gap between'one side of the armature and the corresponding side of themagnetic frame and is supplied with current from a color channel or black channel, depending upon the color of the ink being supplied to the air stream by the nozzle.

Figs. 11 and 11a illustrate one form of coil which may be employed. As there shown, the

, coil is preferably of the thin, pancake type, the

wire being wound on a suitable insulation core, the entire winding being then impregnated with a suitable self-hardening thermoplastic or'thermosetting insulating composition such as Bake lite. The inner terminal ofthe coil may be con nected to a thin metal strip ill? which extends along the surface of the coil to one edge and is there connected to a flexible lead I? l. The other flexible lead to the coil is indicated at H2. The piston Hi is preferably of non-magnetic material. Each coil is preferably yieldingly supported as upon one arm of a make and break switch, indicated at H3, such switch being connected to a pump when desired, as described hereinafter. It will be evident that in the event the moving coil H2 is connected to it correlated electric input signal and in the event the conduit I09 and chamber H0 are filled with ink, movements of the coil H2 and the piston ill carried thereby will result in the imposition of a varying pressure upon the ink in the chamber and conduit, thereby controlling the discharge of ink through the nozzle 35. As the amount of ink in the conduit me and chamber i it is depleted, the piston ill will move upwardly under the yielding influence of the contact switch H3. In order to minimize the inertia of fluid moving through conduit H39 and permit more rapid changes in the magnitude of flow to take place, a capillary choke H5 may be placed between the chamber H0 and the conduit Hi9. Moreover,

under these conditions it would be highly desir-- able to employ a viscous an ink as possible in order to assure a more rapid cut off when it is desired to terminate the discharge of ink. When, due to the depletion of ink from chamber H8, the piston III has moved upwardly sufficiently to close switch H3, a pump (not shown) is energized by closure of such switch, the pump forcing new ink into chamber H through conduit H4 and capillary choke H5.

In actual practice, however, it has been found desirable to employ a relatively viscous pressure applying fluid or liquid for applying pressure to a body of relatively non-viscous ink, such body of ink being then connected to a nozzle. The reason for this arrangement is that if the controlling pressure were applied directly to the relatively non-viscous ink and then suddenly removed therefrom, the ink would continue to flow, being possessed of inertia; thus very poor control of the ink would be had such a system. It is desirable that the instant the controlling pressure ceases or is reduced the ink also stop flowing or the now thereof be coris so great that almost immediately after the 7 pressure is removed from the viscous fluid said fluid stops flowing, and correspondingly, when the pressure applied to the viscous fluid is reduced, the flow of the viscous fluid is reduced almost immediately with very little inertial lag.

However, if the ink is to be supplied through a fine nozzle it cannot be a very viscous fluid but must be relatively non-viscous. Therefore, a compromise is reached in that a pressure applying fluid is used which is relatively viscous and which is adapted to apply pressure through a capillary choke to a relatively non-viscous ink; thus the desired results are attained and inertial lag is minimized.

In the drawing the chamber I I9 is shown connected to a conduit I I4 through a capillary H5. The conduit I id is connected to a source of fluid or to a pump adapted to supply fluid under pressure to the chamber Ht. The fluid so supplied is preferably very viscous and immiscible with the inks being employed. Fluid having viscosity of about 600 poises, such as viscous hydrocarbon oils have been found suitable. In the event the conduit 1 H3 is connected to a pump, such pump is controlled by the switch H3. is for the purpose of inhibiting or reducing return or backflow from the chamber I I8 into the conduit Ht. When the arrangement just described i employed, the piston III acts against the viscous liquid in the chamber H0, such Viscous liquid extending into the conduit Hi9 toward the lower portion of a chamber I I9 so that it causes displacement of the relatively non-viscous ink in the chamber I I9, thus resulting in a flow of ink through the nozzle I05.

Mean for supplying ink to this chamber and to the nozzle I65 are provided and such means may comprise a rotatable member II'I mounted upon the end of the rotatable shaft 85, the member Ii'i being provided with chambers or bores such as the bores 5 I8 and IE9, best shown in Fig. 10, 8 showing the bore or reservoir H9 in alignment and in communication with the conduit I69 and nozzle m5. Variations in pressure in chamber HI) (produced by minute move- The capillary H5 ments of the piston III) are thereby transmitted by the heavy viscous fluid to the ink in the reservoir H9 and cause regulated discharge of ink through the nozzle I05. It is understood that the presence of the capillary I I6 will absorb most of the pressure generated by piston III in the chamber II!) so that the variations in pressure between the capillary H5 and the nozzle I05 are of a very low order in comparison with the pressures in the chamber H8. More rapid changes in flow through the nozzle are thus attained without the inertia effects which would normally be expected. Since most inks are somewhat compressible, it is desirable to make the reservoir I I9 relatively small and to supply fresh bodies of ink in timed relation with the rotation of the reproducing drum 33. This is accomplished by periodically and alternately introducing the bores H8 and H9 in alignment with the nozzle I05, one of the bores supplying ink to the nozzle while the other is being flushed and recharged.

In Figs. 6', "I, 8, ac and 1c the reservoir Iis is shown in alignment with the oil conduit I99 and the ink nozzle 25. The reservoir H8 is in an inoperative position with respect to the nozzle but it is in a recharging position and flushing position with respect to an ink supply which is being passed through the reservoir H8 and discharged therefrom. One such ink supply line in its relationship to reservoirs I I8 and I I9 is shown So. It will be noted that the upper block iii! is provided with a port I20 adapted to be connected to a source of ink or an ink pump, such port E28 communicating with conduit I2I having branches 522 and I23 and vertical ducts I24 and whose open ends abut the upper surface of the rotatable member III. In the position shown in 9a port I20 is in communication with reservoir I I8 of the rotatable member I II by conduits I2I, I23 and I25. i he lower block N0 of the reproducing head is provided with conduits or discharge tubes I26 and IE1 which join and extend downwardly through the armature B2 and communicat with discharge ports such as the port i223 formed in the supportin bracket of the device.

Discharge port IE8 is in communication with an ink storage reservoir. The ink is pumped from this reservoir through a plug of cotton or glass wool in order to remove any drops of oil which may be present and is then passed through a chamber for the separation of any possible air bubbles. The ink then flows into port I29, out of port I28 and backinto the storage reservoir. Oil which has been flushed from the ink reservoirs its and H5 accumulates in the storage reservoir either above or below the ink according to its density. Periodically the oil is drained from the storage reservoir and the ink is replenished. The ink pump may be a small diaphragm pump such as an automobile gasoline pump.

The circular element I I1 is partially rotated in timed relation to the means for driving the re producing drum so as to periodically introduce a bore filled with fresh ink into the ink conduit leading to a nozzle. In Fig. 9a the bore H3 is shown being iiushed whereas bore H9 has been introduced into the ink conduit. When the circular irieinber II'. is partially rotated it will be rotated so as to move the bore I IS in alignment with the flushing bore I24, the refilled and recharged bore H8 being then placed in alignment with the ink conduit I09. Preferably the bores H3 and H9 are spaced a distance equal to their diameter along the arc of their movement so that the change from bore I Is to I I 9 and vice verse. is almost instantaneous.

It is to be understood that although the conduits associated with nozzle I95 have been described in detail, similar arrangements of conduits, forks and channels are associated with each of the other nozzles.

Fig. 10 discloses means for supplying a lubricating oil to the periphery of the intermittently, partly rotated circular member I, a suitable sealing ring 228' being positioned around the member to prevent oil leakage between the blocks N38 and IIEI. Also, in order to provide for the iiow of this lubricating oil a hole is provided in member II? from its outside edge or periphery to its centrally located square hole. The pressure of the oil in the sealed chamber thus formed is maintained at a value greater than the maximum pressurein any of the ink reservoirs. By this means the inks are prevented from leaking out along the sliding surfaces of member III. Instead, the lubricating oil leaks into the reservoirs along the sliding surfaces, but due to the high viscosity of the oil the leakage is negligible.

The reproducing head of this invention is adapted to be used in making colored facsimiles or reproductions. As more particularly pointed out in the before mentioned parent application, Serial No. 426,220, now Patent 2,413,706 issued January '7, 1947, a plurality of color separation photographic images may be scanned by suitable scanning means including electron multiplier photocells, the output of which may then be fed into suitable logarithmic amplifiers. The output from the logarithmic amplifiers may then be fed into a suitable mixer adapted to similarly modify all of the color signals so as to reduce the color signal corresponding to the least ink coverage, to a value corresponding to no ink coverage. The mixer is also adapted to generate a black output signal corresponding to said modification of the color signals.

The modified color signals may also be corrected for th overlapping of the color absorption characteristics of the colored inks to be used in reproduction. The color signals and the black signal may then be fed into the reproducing head of this invention as set forth below.

The color reproduction system described in co pending application, Serial No. 702,173, filed October 9, 1946, which is also a continuation-inpart of said parent application, Serial No. 426,220, new Patent 2,413,706 issued January 7, 1947, is also adapted to cooperate with the reproducing head of this invention. Said system functions in a manner somewhat similar to the system described in said parent application.

In general, therefore, each of the moving coils, such as the coil H2, is connected to its separate color input electric signal and controls the supply of ink to a nozzle. Mounted above the nozzles is a shield I39 having a minute opening or perforation I31 therein, said perforation being in axial alignment with the air conduit I53. The reproducing drum may either be in contact with the shield I3II or slightly spaced therefrom. Ink supplied to the upwardly directed air stream is virtually atomized and blown against the shield I38, a desired proportion of ink passing through the aperture I ill and forming the desired spot or line of suitable color on the paper carried by the reproducing drum 33. Mixing of difierent colored inks takes place in the air stream and the distance between the tips of th nozzles and the 8 shield I39 should be suificient to permit mixing of the inks before they pass through the aperture ISI. In order to give the finest possible spray the inks may be liquids of low viscosity and low surface tension such as solutions of dyes in methyl alcohol.

A second embodiment of the reproducing head of my invention is shown in Figs. 14 and 15 and the electrical control circuits therefor being shown in Figs. 16 and 1'7. The reproducing head shown in Figs. 14 and 15 contains four ink reservoir wheels or rotatable members (one for each ink), three of which are shown as I 4|, I42 and I43 in Fig. 14. Each of these wheels is mounted for rotation by means of a shaft I44, I45, I46 and IdI, which extends through the block I48 and has a driving gear mounted on the other end thereof such as gears I49 and I 5t shown in Fig. 15, it being understood that the other two shafts are also provided with suitable driving gears. These four gears intermesh with each other so that if one shaft turns, the other must turn also. A suitable driving means is connected to the shaft I55 so that the four ink reservoir wheels may be rotated at a suitable speed.

The holes in the ink reservoir wheels (best shown in Fig. 14) form the ink reservoirs or chambers and each ink reservoir or chamber is flushed out at each revolution with the corresponding ink. This is done as follows: Assuming that the ink reservoir wheel hi3 rotates in a clockwise direction, the ink enters a port I5I in the block it and flows upward through the ink reser voir in line with this port into slot I52 in the upper plate I53. Next it flows down through the ink reservoir opposite the port I54 and then flows out at port I55. It may be mentioned that a suitable pump such as a small centrifugal or gear pump and a large ink reservoir may be provided for flushing the ink from each of the ink reservoir wheels. The ink in each of these large reservoirs is maintained at uniform temperature by suitable means. Such means are well known in the art and need not be shown.

Positioned around the four ink reservoir wheels and between the upper plate I53 and the lower block I58 is an annular ring I55 adapted to seal in and enclose the space containing the four ink reservoir wheels. Passing longitudinally through the lower block Hi8 and through the enclosed chamber containing the ink reservoir wheels and through the upper plate I 53 is an air conduit I56 adapted to be supplied with air under pressure from suitable means not shown.

Positioned upon the upper plate I53 are four nozzles (two of which, I57 and I53, are shown in Fig. 15 connected to tubes I59 and IE0 which pass through the plate .I 53 to points opposite their ink reservoirs, it being understood that the other two nozzles are also provided with similar tubes and that all of said tubes may be capillary tubes). The nozzles are provided with tiny spray jets or orifices inwardly directed toward the air stream emitted by the air conduit I56 so as to be atomized and mixed thereby. The atomized, mixed inks are then adapted to be sprayed through a suitable shield upon a suitable medium such as paper or the like, mounted upon a rotatable, axially movable, driven drum, such as shown in the first embodiment of this invention.

The flow of each ink to the corresponding nozzle or spray jet is caused by heating and expanding it by the passage of a high frequency alternating electric current. The ink reservoir wheels are made of an electrical insulator such as methyl methacrylate resin or other suitable material and the upper electrode for each wheel is the plate I53 whi'ch'is made or metal or other suitable electrically conductive material. The lower block M8 is also preferably made of some suitable insulating material such as methyl methacrylate resin, phenol-formaldehyde resin or other similar material.

Lower electrically conductive electrodes are mounted in the lower block 48 and are shown at Y liil, IE2, H53 and its. These electrodes are provided With insulated leads or connecting wires I55, ltd, llil and IE8. The heating cycle for each reservoir is that portion of its path in which it is in contact with its corresponding electrodes. The upper plate I53 is slotted so that the ink chamber or reservoir is connected to its tube and to'the spray jet of a nozzle during all parts of its heating cycle when the lower electrode is in contact with the ink. The flow of ink to the spray jet of the nozzle is then caused by passage of the corresponding electric current. The flow is proportional to the rate oi heating or to the current squared multiplied by the resistance, in which the current is the actual current passing through the ink in the ink chamber or reservoir and the resistance is the effective resistance between elec trodes in the ink chamber or reservoir. This heating effect may be greatly increased by dissolving salt or the like in the ink for increasing rlow of the ink behind the electric current passed therethrough. Also, since the electrical load is a resistive one, there can be no lag in current behind applied voltage due to inductive or capacitive effects. Practically all of the time lag in the flow will then be due to the compression of the liquid due to the change in pressure on the liquid occurring with changes of heating rate and changes in flow of the liquid. This effect can be reduced to a negligible value by making the volume of liquid connected to the spray jet of the nozzle suificiently small.

It should be noted that the effect of heating losses from the liquid to the container are minimized until. they are negligible. This is done because the heating chamber is separate from the tube carrying the ink from the ink chamber to the spray jet of the nozzle. At the beginning or the heating cycle the temperature or the ink is the same as that of the ink chamber so that the heat transfer is zero. passed through the liquid and heat is generated in the liquid, the temperature of the liquid rises and the heat transfer from the liquid to the ink chamber becomes greater and greater. As soon as the temperature of the ink reaches a point at which the heat loss from the ink causes an appreciable error or reduction in the flow or the ink from the ink chamber, then the ink reservoir wheel revolves and a new ink chamber is substituted for the old one. The ink in the ink cham her now has the same temperature as the walls of the ink chamber so that heat loss is zero and no error results from heat loss.

Although I have described the construction and operation of one ink reservoir, spray nozzle As the electric current is a 10 and associated elements, etc., corresponding to one ink channel, the description also applies to the other three ink reservoir wheels, spray nozzles and associated .parts.

Referring to Fig. 16, a diagrammatic electrical block drawing is shown indicating the manner in which the high frequency heating of the liquid in the ink chambers of the reproducing head shown in Figs. 14 and 15 may be accomplished. Referring to said Fig. 16, a radio frequency oscillator 225 is adapted to generate a suitable high frequency alternating current which is fed into a modulator 226. An input signal indicated at 22'! is also fed into the modulator for controlling the high frequency alternating current. The modulated radio frequency output from the modulator 226 is then fed into a power amplifier 228 and is then fed from the power amplifier 228 to the upper and lower electrodes corresponding to one color channel of the reproducing head indicated at 229. Although the diagrammatic electrical block drawing Fig. 16, shows the system applied to one channel only, corresponding to one ink, the description applies equally as well to the other three inks.

Fig. 1'7 illustrates one form of modulator such as that generally indicated at 225 in Fig. 16. The

input signal corresponding to 221 in Fig. 16 is applied to input terminal 230 in Fig. 17. The input terminal 230 is connected to the grid 23! of a phase inverter tube 232. The cathode 233 of the phase inverter tube 232 is connected through a suitable cathode resistor 234 to negative power input terminal 235. The anode 236 of the phase a inverter tube 232 in connected through a plate resistor 23! to positive power input terminal 238. The anode 236 of the phase inverter tube 232 is also connected through a resistor 239 to the control grids 240, 241, 242 and the anodes 243. 244 and 245, respectively, of electron tubes 246, 241 and 248 and through radio frequency transformer secondary winding 249 to the grid 250 of the modulator 25L The before mentioned grids, anodes and oscillator transformer secondary winding are also connected through a resistor 252 to negative power input terminal 253. The cathode 254 of the electron tube 246 is connected to negative power input terminal 255. The cathode 256 of the electron tube 241 is connected to negative power input terminal 251. The cathode 258 of electron tube 248 is connected to negative power input terminal 259. The cathode 250 of the modulator tube 25l is connected to negative power input terminal 26! The anode 262 of the modulator tube 25! is connected through the primary winding 263 of an output frequency transformer to positive power input terminal 264. The primary winding 255 of the oscillator radio frequency transformer has the opposite ends thereof connected to input terminals 266 and 261 which are adapted to be connected to radio frequency oscillator which is not shown since such oscillators are well knownin the art. The secondary winding 268 of the output radio frequency transformer has the opposite ends thereof connected to output terminals 269 and 210 which are adapted to be connected to the upper and lower electrodes at the upper and lower ends of one ink chamber in the reproducing head shown in Figs. 14 and 15.

Similar systems are utilized for each of the other ink channels. One essential requirement of the modulator is that it modulate the high freaeaai'eo quency alternating voltage in such a way that the output voltage from the modulator is proportional to the square root of the input' signal voltage. This is due to the fact that the heating effect of the current passed through the ink in the reproducing head is proportional to the current squared times the resistance of the ink.

In the system shown in Fig. 17, the phase inverter tube 232 is used so as to cause the reproducing head to produce an increase in the flow of ink in response to a more negative input signal. The phase inverter tube may be dispensed with entirely if it is desired to have the fiow of ink from the reproducing head function oppositely from that described.

The electron tubes 256, 241 and 248 together form a virtually square root amplifier. Each of the tubes 246, 24'! and 258 acts as a rectifier and draws current when its grid is more positive than its cathode. This causes a reduction in the rate r of increase of grid voltage of the tubes 246, 241, 2:38 and the modulator tube 25! with constant rate of change of the grid voltage of the phase inverter tube 232. By adjusting the voltages of the cathodes 255, 256 and 258 of the three electron tubes 245,251 and 248, respectively, to the proper values, a nonlinear amplification may be obtained which may be made to closely approximate a square root curve. Thus, the output at terminals 259 and 270 is a radio frequency alternating current so modulated that the heating efiect thereof will vary linearly with the input signal delivered to input terminal 236.

It should be emphasized that numerous possible modifications of the second embodiment of For example, in the first embodiment of my invention, only a single ink reservoir wheel or rotatable member is utilized which oscillates back and forth, whereas in the second embodiment of this invention individual rota-ting ink reservoirs are used, one for each ink and they rotate continuously in a given direction. The said system employing four rotating wheels may be incorporated in the first embodiment of my invention with the means for causing the ink flow being the piston enclosed within a cylinder and actuated electro-magnetically,- as shown in the first form of my invention. Also, if desired, the second high frequency heating form of my invention may utilize a single ink reservoir wheel oscillated back and forth in the mannershown in the first embodiment of my invention. If desired, the second form f my invention employing electrical heating of the ink for causing corresponding ink fiow variations may be employed in conjunction with portions of the first form of my invention. For example, such electric heating means may be employed for heating the liquid contained in the chamber H9 of the first form of my invention in place of the electromagnetically controlled piston heretofore described and illustrated in the first form of my invention.

The examples describedand illustrated herein are exemplaryv only and are not intended to limit the scope of this invention which is to be l mi only by the appended claims. I

I claim:

1. A. reproducing head adapted for use in the reproduction of pictorial representations, comprising: a movable coil in a magnetic field, said coil being permitted minute movements responsive to electric signals flowing therethrough; an air conduit; means for supplying air under pressure to said conduit; a nozzle provided with a fixed opening directed into the air stream from said air conduit; an ink conduit communicating the nozzle with a source of ink; an enlarged chamber formed in said head; a third conduit communicating said source of ink with said enlarged chamber; and a piston in the enlarged chamber, said piston being operably connected to said movable coil.

2. In an apparatus of the character defined in claim 1: means for supplying a viscous fluid to the enlarged chamber; and a capillary choke in said third conduit between said chamber and the said source of ink. I

3. In an apparatusoi the character defined in claim 1: means for supplying a viscous fluid to the enlarged chamber; a capillary choke in said-third conduit between said chamber and the source of ink; and means positioned between the fixed opening of the nozzle and said choke for supplying ink to said ink conduit.

4. A reproducing head adapted for use in the reproduction of pictorial representations comprising: a. field coil; a magnetic frame and armature adapted to generate a magnetic field; a movable coil suspended in the magnetic field between said frame and armature, said coil being permitted minute movements responsive to electric signals flowing therethrough; an air conduit; means for supplying air under pressure to said conduit; a nozzle provided with a fixed opening directed into the air stream from said air conduit; an ink conduit communicating the nozzle with a source of ink; an enlarged chamber formed in said head; a third conduit communicating said source of ink with said enlarged chamber; a capillary choke in said third conduit; and a piston in the enlarged chamber, said piston being operably connected to said movable coil whereby movement of the piston in said chamber controls the pressure of ink in the conduit leading to the nozzle and the flow of ink therethrough.

5. In combination with the apparatus defined in claim 4: a fluid supply line to said enlarged chamber; a pump in said line; a capillary choke between said pump and enlarged chamber and adjacent said chamber; and means controlled by the position of the moving coil for energizing the pump.

6. In combination with the apparatus defined in claim 4: means for supplying fresh ink to said ink source, said means being positioned between said enlarged chamber and the fixed opening of the nozzle.

7. In combination with the apparatus defined in claim i: means for supplying fresh ink to said ink source, said means being positioned be tween said enlarged chamber and the fixed opening of the nozzle; said means including a rctatable member provided with bores adapted to be inserted into communication with said ink con duit alternately; and means for flushing the bores not in communication with the ink conduit.

8. A reproducing head adapted for use in the reproduction of pictorialrepresentation com" prising: a field coil, a magnetic frame and arma ture adapted to generate a magnetic field; a movable coil suspended in the magnetic field between said frame and armature; an air conduit; means for supplying air under pressure to said conduit; a nozzle directed into the air stream from said conduit; an ink conduit communicating the nozzle with a source of ink; an enlarged chamber formed in said head; a third conduit communicating said source of ink with said enlarged chamber; a viscous liquid in said third conduit and chamber; a capillary choke in said third conduit; a piston slidably mounted in said enlarged chamber, said piston being operably connected to said moving coil; and means for supplying viscous liquid to the enlarged chamber.

9. An apparatus for controlling the flow of a relatively non-viscous liquid through an orifice comprising: a conduit for supplying the orifice with the non-viscous fluid; a chamber adapted to contain a relatively viscous liquid, said chamber being connected to said conduit by a capillary choke; means for controllably applying pressure to the viscous fluid in the chamber for forcing same through the capillary choke and displacing the non-viscous fluid in the conduit; and means for supplying the conduit with the nonviscous fluid at a point between the capillary choke and the orifice.

10. A reproducing head adapted for use in the reproduction of pictorial representations in response to an input electric signal comprising: an air conduit; means for supplying air under pressure to said conduit; a nozzle provided with a fixed opening directed into the air stream from said air conduit; an ink conduit for supplying the nozzle with ink; means in said ink conduit for replenishing the ink therein, said means including a movable member provided with a plurality of parallel bores adapted to be sequentially inserted into said ink conduit and means for flushing the bores not in communication with the ink conduit; and means continuously responsive to said input electric signal for causing flow of ink out of the nozzle at a rate virtually corresponding to said input signal.

11. A reproducing head adapted for use in the reproduction of pictorial representations in response to an input electric signal comprising: an air conduit; means for supplying air under pressure to said conduit; a nozzle provided with a fixed opening directed into the air stream from said air conduit; an ink conduit for supplying the nozzle with ink; means communicating with said ink conduit for supplying ink thereto, said means including a movable member having a plurality of bores formed therein, said member being adapted to insert, sequentially, each of said bores into communication with said ink conduit, and means for replenishing the ink in a bore not in communication with the ink conduit; and means continuously responsive to said input electric signal for causing flow of ink out of the nozzle at a rate virtually corresponding to said input signal.

NORMAN R. GUNDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,306,985 Williams June 17, 1919 1,627,701 Hall May 10, 1927 1,995,424 Guiness Mar. 26, 1935 2,013,639 Steinhart et al. Sept. 3, 1935 2,100,204 Shore Nov. 23, 1937 2,143,376 Hansell Jan. 10, 1939 2,157,549 Lindenblad May 9, 1939 2,172,539 Kimmich Sept. 12, 1939 2,175,869 Bernarde Oct. 10, 1939 2,404,217 Collins July 16, 1946 2,410,692 Strobell Nov. 5, 1946 2,433,812 Hastings et a1 Dec. 30, 1947 

